[clang] [clang][CodeGen] Use guarded init for weak static locals without constant initialization (PR #226645)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

> Dropped the EmitGlobalVarDefinition change, which caused the dllexport-members.cpp failure. Inline variables might have a similar issue; should I handle that here or in a separate PR?

 Inline variables have the same issue, yes.  I'd prefer to handle it now, while I still have the relevant context in my head.

https://github.com/llvm/llvm-project/pull/226645